About this replacement
Asus Q302L Series — 11.3V Li-Polymer Replacement Battery (C31N1339)
This is an 11.3V, 4000mAh (45.2Wh) Li-Polymer replacement battery for the Asus Q302L, Q302LA, Q302LG, and Q302LA-BBI5T14 notebook laptops. It replaces OEM part numbers C31N1339, 0B200-00930100, 0B200-00930200, and 0B200-00930300. If the original cell has degraded and the laptop no longer holds a charge unplugged, this cell restores portable operation.
- Q302 series platform fit: The Q302LA, Q302LG, and Q302LA-BBI5T14 all share the same three-cell Li-Polymer pack configuration, matching connector pinout, and BMS handshake protocol — which is why a single part number covers the entire range.
- Bench tested on actual hardware: We cycled this cell on the Q302L platform and confirmed the BMS negotiation completes correctly — the system identifies the battery, charge current ramps as expected, and the protection circuit trips at the correct cutoff threshold.
- Post-swap recalibration cycle: After fitting this cell, run the laptop down to hibernate cutoff under normal use, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell and clears the inaccurate health warning that appears after every cell swap.
BIOS reporting poor battery health immediately after replacement
The Q302L BIOS stores battery health data in EEPROM on the old cell. When a new cell goes in, the BIOS reads stale cycle count and degradation values from its own memory and flags the battery as poor before a single cycle has run. This is a firmware read issue, not a fault with the replacement cell. Running one full discharge-to-hibernate followed by a full uninterrupted charge forces the BIOS to rewrite that EEPROM data against the actual new cell. After one complete learn cycle, the health status updates and the warning clears.
Laptop shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The IC maps a legacy discharge curve to the new cell and calls the voltage floor too early — cutting power while the display still shows charge remaining. It is not a dead cell. Run two to three full discharge-to-hibernate cycles with no interruptions and the fuel gauge recalibrates its low-voltage threshold to match the actual chemistry. After calibration, the shutdown point shifts back to the correct cutoff near 10.0V per pack.